Practical plane and solid geometry for advanced students, including graphic statics, adapted to the requirements of the South Kensington syllabus (1899)
Harrison, Joseph, Baxandall, George Albert · London Macmillan · leaf 166
axes intersecting in P. Observe that whichever method of plotting be adopted,in each case we measure from the axes 3 units to the rightand 5 units upwards, in order to arrive at the position of P. Suppose now the point were at P2, the distances of 3 and5 units from the axes being the same, but… … \-PA(3,-5) The convention adopted is to prefix the minus sign tothe co-ordinates of P2, writing them - 2 and - 3, andconsidering each as a negative quantity. We should thusspeak of the point P„ as the point ( - 3, - 5). We might plot the point P2 in any one of the threeways described for P; but in…
